Dark Lines, Rectangular Stains on Indoor Walls or Ceilings Ghosting Stain FAQs

Thermal tracking stains Q&A

Hidden Damage Risk When Evaluating Indoor Stains FAQs

Warped, wavy, soft floors, lumpy walls, ghosting stains, possible water damage

My husband and I are currently painting the inside of a friends manufactured home (1999) that they are selling

While working we noted some odd and concerning issue's.

First several areas of the floor are soft and wavy, the walls in the 2 small bedrooms are literally warped horizontally when painting with a roller it was like going over speed bumps, in the master bedroom and bath there are signs of severe ghosting on walls and ceilings where we can actually see the complete outline of the frame.

I personally believe there could be water or moisture damage.

Also it has taken at least 3 coats of premium paint with primer to cover even the walls with no visible sign of problems...the paint won't stick and this is an issue we have faced before where there was excess moisture in the walls.

I am not an expert by any means just going on past experience and have seen how water or moisture damage can get into a mobile or manufactured home undetected. I shared my thoughts and concerns with our friend and they were upset it seems with us for sharing and we only suggested looking into it.

are going to have an inspection done so can you give me suggestions on any particular type of inspection they should have done or even testing in the home for mold? Thank you from Washington State USA On 2019-06-27 by Lisa P

by (mod) - painting the inside of a manufactured home for sale: problems to avoid

As you suspect a moisture problem that makes sense to have a thorough Home Inspection performed.

The scope of that includes looking for leaks, moisture sources, moisture trap, and improper or blocked ventilation.

Watch out: drywall that has been wet may be mold-contaminated on the hidden side - some tests cuts as well as an inspection of the attic or under-roof space will be needed to evaluat the conditions there.

Don't continue renovating before diagnosing these problems as your work could be wasted and could have to be done over again.

Painting Over Ghosting Thermal Tracking Stains FAQs

Will black ghosting stains in our home in Australia reappear after we clean and paint the stained surfaces?

I just read your article on Thermal Tracking, Bridging and Ghosting, and believe I may have this problem in my home.

I've had several builders around to look, and none of them have ever seen anything like it.

We've owned the house for 3 years now, and it seems to have started around winter last 2015 (I live in Australia so May/June). We don't have any open fireplaces or anything, just 2 reverse cycle air conditioners.

We recently cleaned out the filters on the living room air conditioner and it was filthy, so I was wondering if they may have been contributing to the problem. The house was poorly insulated, however I insulated the entire ceiling around June of 2015.

I recently cleaned some areas of the house with sugar soap and warm water, and the marks appear to come off, or just smudge around the wall/ceiling. Are you able to tell me what you think the problem might be, and the solutions to fixing it.

It seems to be slowly spreading to other areas of the house also. We were going to repaint the ceiling and walls, but I just want to know what this is and if it will come back again after I've repainted it. - T.D. 2016/01/03

Reply: Yes stains will recur until we correct the causes of thermal tracking or ghosting

Yes the chimney effect caused by the holes cut into a ceiling to mount pot lights (recessed ceiling lights) will increase the air movement around and up through each light, increasing deposits of building dust and soot thereon. But the root causes of thermal tracking remain those listed at the top

of GHOSTING DARK STREAKS or LINES: CAUSES

For a guide to cleaning, covering, painting, and preventing these indoor stains on walls and ceilings please see

THERMAL TRACKING REMEDIES for details

Watch out: I agree that you don't want to insulate over recessed lights if they are not rated for that application as doing so can cause overheating or even a fire; and changing all of the recessed lights to those rated for direct contact in an insulated ceiling (DCIC) so that they can be insulated over is a desirable improvement but not a cheap one.

But if we don't correct the causes of thermal tracking or ghosting it will return after cleaning and painting.

Reader follow-up:

I've been up in the roof today, and there are areas around the downlights that aren't insulated, but they've been left there so that we don't start a fire in the roof from the insulation coming into contact with a hot surface.

I will have to look at some heat shields for the downlights so we can insulate the entire area.

Another interesting thing, which I think could be a definite problem is the exhaust fan duct from the kitchen goes into the ceiling but doesn't go any further, so any hot, fatty, humid air from Cooking goes into the ceiling but can't escape.

Could this be coming back down through the holes for the downlights and sticking to the ceiling causing these marks?

The downlights do have a black sticky residue around them that spreads when touched with a wet cloth.

Reply:

Watch out: Venting a kitchen exhaust into a ceiling not to outside is unsafe and probably violates your local building codes. Over time the accumulation of grease can cause a building fire. I would stop using the fan entirely until it can be vented to the outdoors.

You typically need 3" of clear un insulated space around the ceiling pot lights but the light fixture should contain a label with the specific clearance distance for insulation; Those large dark rectangles on the ceiling suggest large cold areas of missing or incomplete insulation.

If it were my home I'd change over to DCIC rated lights that can be covered by insulation.

Insulation leaks & thermal bypass defects:

We use thermal tracking marks on an area where insulation is visible to identify and correct air bypass leaks, thus saving energy or reducing home heating or air conditioning costs.

Details about air leaks in buildings are discussed

at AIR BYPASS LEAKS.

Building air leak testing is described

at BLOWER DOORS & AIR INFILTRATION

and at AIR LEAK DETECTION TOOLS.

Insulation adequacy: Clues that suggest Insulation adequacy can be picked up easily if the observer will use thermal tracking marks on larger areas of interior walls or ceilings to tell us areas of the building that are not insulated, or are not well insulated - areas where we should consider adding or improving insulation to save energy by reducing building heating or cooling costs.

See INSULATION INSPECTION & IMPROVEMENT for more information.

Usually soot marks, thermal bridging, or thermal tracking stains appear, if at all, in the building interior locations listed just below discussed in the remaining sections of this article.

Ghosting Stains & Missing Insulation FAQs

How can I fix these ghosting or thermal tracking lines and rectangles on ceilings - not from a roof leak

Hi, I have noticed this strange rectangular stain on my vaulted ceiling recently. I noticed these on a dry day ( no rain for few days). I believe the humidity inside the house was high as no AC was on for 10/15 days.

Could this be thermal tracking? Also when I tried touching those area in a hot sunny day, I felt some points felt warm to touch then the rest of the ceiling.

Same area I touched after a heavy rain, didn’t felt wet, but it didn’t felt warm that day. Any idea if it is due to missing or insufficient insulation on vaulted ceiling?

How can I fix these dark ceiling stains? Who can check if it is an air leak? The roofer after seeing this confirmed that it is not a roof leak and suggested to get it painted.

Reply by (mod) - add missing insulation

Those look like thermal tracking or ghosting stains, associated with the combination of air leaks or voice and insulation and of course an indoor source of dust or switch or debris.

An inspection of the under-roof area will include looking for voids in the insulation, missing insulation, roof leaks, attic moisture, and mold contamination.

Even with no roof leaks or high indoor moisture, insulation voids alone combined with normal indoor dust levels and air movement can produce the ghosting stains in your photo. But those rectangular stains are about the same as the width between ceiling joists - I suspect insulation is thin or missing in those areas.

Please see THERMAL TRACKING REMEDIES for details -

and let me know if you have further questions.

Thermal Tracking Stains at Electrical Outlets FAQs

Diagnose black lines on walls above electrical receptacles

I have dark lines coming from above every plug socket and switch in the kitchen. They go up to the ceiling? On 2019-04-24 by Jon Robertshaw

by (mod) -

Perhaps with some photos of the stains and some information about the building country, city (*thus climate), age, type of construction (wood frame, insulated wall cavities0 etc. one can make a useful diagnosis.

There could simply be air leaks at those receptacles, but

Watch out: black stains at electrical receptacles could indicate overheating electrical wires, unsafe connections, and a shock or fire hazard. So it's worth hangin an electrician examine one or more of those devices to assure there's no electrical hazard.

Kitchen stains are also often related to deposits of soot or grease or smoke or even just the effects of moisture from cooking. As in the article above, such deposits can mark stud locations.

Watch out: some indoor soot sources can indicate dangerous conditions, such as soot produced from improperly adjusted or vented gas burners.

At THERMAL TRACKING BRIDGING GHOSTING - home

you will read more explanation of how and why thermal tracking type stains appear on walls. Please take a look there and let me know what questions remain.

Ghosting Stains at Ceiling Lights FAQs

What are these dark stains around our ceiling lights?

We just moved in to this house, that is full of round patches.

Can someone Identity the problem. On 2018-02-01 by Alicia -

Reply by (mod) - thermal tracking or ghosting stains: air leaks around recessed ceiling lights - pot lights

Alicia

From your photo I would say it's pretty likely that those recessed ceiling lights have had insulation pulled-back (avoiding an overheating light fixture and fire hazard).

Air leaks are common around recessed ceiling lights and are worse when the opening cut for the light is not sealed against air leaks, and are exacerbated by the use of older ceiling lights that, for fire safety, can not be covered by attic insulation.

The result is a chimney effect that increases heat loss as well as a cool spot on the ceiling where moisture and dirt adhere - it's a good example of thermal tracking discussed in this article.

You show that the spots can appear not just in lines but in whatever pattern of cool area occurs in a ceiling or wall.

If this were my house I would consider installing DCIC-rated ceiling lights so that they can be safely insulated-over, and I would seal the light cutouts against air leakage.

See RECESSED LIGHT CLEARANCES

Thermal Tracking Stains & Roof Leak FAQs

Do thermal tracking stains always mean mold contamination of the roof was leaking?

If I have thermal streaks on the wall should I also assume that I have mold in back of the wall, since I have had a leaking roof which is now fixed? On 2016-06-17 by Laura

Reply by (mod) - roof leaks - mold risk

Thermal tracking does not mean that there is always mold contamination in the same area as the streaks; those are surface depositions of dust from temperature differences + slight moisture differences on the surface.

But

Watch out: if there was a roof leak that sent water into the wall cavity, that needs to be explored from above or by test cuts because mold contamination is quite likely.

Also any insulation over moldy drywall should be assumed to be moldy and will need to be removed, the surfaces cleaned before the insulation and drywall are restored.

Vehicle Exhaust & Ghosting Stains FAQs

Thermal tracking on garage ceiling caused by car exhaust?

Wow, what a great resource, thank you so much for all the info!

Question: Garage ceiling has this tracking at all the drywall seams.

I can see that the ceiling was insulated. Dark spots exactly correspond with the 12" joint compound finishing knife.

Could it be that the compound was simply not sealed properly when it was painted? Also, could exhaust from cars cause this-it's nowhere else in the house.

Thanks, I love this site! (Oct 2, 2014) Sam

Reply:

Sam

I don't think the stains are caused by poor sealing of the drywall seams.

More likely the drywall joints are over wall studs, pipes, or other (less-insulated) cooler surfaces that pick up a bit more moisture and thus particle deposits thus stains.

Yes car exhaust could be a particle source, also a moisture source. And if the car is burning oil and is left running for some time in the garage these effects would be increased.

Diesel exhaust probably produces higher levels of carbon and soot so might also be a factor in staining in garages.

Watch out: for potentially fatal carbon monoxide hazards if car exhaust can enter the home or accumulate in the garage.

Thermal Tracking Stains at Seaside Properties FAQs

Black stains by thermopherosis? by deionisation from sea spray?

A friend has black deposits appearing evenly on vertical surfaces at the top of an internal lounge wall, just under the coving. The wall-hung pictures also have severe dirt 'shadows'.

The appearance is similar to that I experienced when I had a de-ioniser in use in my bedroom, but there is none in the friend's lounge but there is a tv and modern wall-hung logfire-effect unit.

Heating is by conventional hotwater radiators. The house is right on the sea front (at Bude) and fully exposed to off-sea winds.

Could the cause be thermopherosis? Caused by deionisation from sea spray? Or what? And what might the solution be? No nearby pollution source that I can identify. (Jan 17, 2012) John Dabbs

Reply: role of sea salt (in air), ionization, or gas burners in indoor thermal tracking stains

John, if by "appearing evenly" you mean at even spaces or intervals such as marking the intervals of building framing members, that would be a classic diagnostic clue indicating thermal tracking.

And yes, using a "de-ioniser" (more likely it was an ionizer - a device that puts an electrical charge on dust particles, causing them to plate out on wall and other building surfaces) can contribute to soot and thermal dust tracking stains on building walls and ceilings.

I'm not sure of the role that off-sea winds would play in thermal tracking - it depends - for example on the effect of winds on building heat loss.

Sea spray itself sounds an unlikely cause of black stains to me as I don't imagine much sea spray actually enters the building interior.

However salt deposits on building surfaces might indeed act as a moisture absorber from damp sea air, increasing the moisture level of those surfaces that in turn increases the rate of dust deposition and thus increases thermal tracking stains.

Even common house dust will be enough of a particle source to explain thermal tracking in buildings, but where there are additional dust or particle sources the effects will appear more rapidly and at more extreme levels.

Examples include an oil burner that is not working properly, producing soot; use of candles, scented candles, woodstoves, fireplaces, or even burning cooking materials. Pets can also be contributors.

Watch out: a malfunctioning gas burner that is producing soot is very dangerous, risking fatal carbon monoxide poisoning so be sure any gas burning equipment has been checked by an expert.

The solution to thermal tracking includes:

- identify and remove sources of high levels interior dust or particulate debris as much as possible

- identify locations of building air leaks and heat losses and correct them

- add insulation, particularly where there are voids

- monitor and correct high levels of interior moisture

Reader follow-up:

Many thanks indeed, Dan, for your comments. Perhaps I should have said that the staining is "uniformly" spread ie a consistent level along the upper perimeter of the room, graduating in intensity as the ceiling is approached.

The wall construction is, I believe, solid masonry (I'll check that), and the effect is apparent on all walls whether internal or not. One wall - facing the sea - has a large double-glazed sliding patio door and a "soot" film appears on this after only a few days after cleaning.

Yes, I should have referred to an ioniser - I apologise! It was because of the similarity of this problem to my previous experience with one of these that I was wondering if this was due to an ionising effect somehow. Hence I was wondering if excessive sea spray could cause ionisation? Clutching at straws?

The household has a cat, but it's a large, open house. The room is clean with few furniture pieces, all modern, with a fitted carpet.

There are a few nearby properties, all as far as I know with natural gas heating.

Completely residential area, and I can't identify an probable sources of dirt/soot particles, but I'll have another look around.

No woodfires, candles or oil burners. Two of the walls have hot water radiators fixed to them, but the staining is at the same level on a third wall with no heating fixed to it.
Any further thoughts?

Ghosting Stains & Gas Stoves FAQs

Ghosting stains due to a gas stove in an all electric house?

We have a friend with a house that has ghosting at the 2nd floor ceiling and top 1-2' of wall where it meets the ceiling; the nails are also popping at this ceiling/wall juncture.

The house is entirely electric with exception of a gas fired stove in the lower level of the split level home.

Do you think the ghosting is due to a malfunction with the stove or some other issue? thank you Apr 7, 2012) sue white said:

Reply:

Not likely - but

Watch out: a gas cook stove that is making visible soot is not working properly and is unsafe, risking fatal carbon monoxide poisoning.

 

Ghosting Stains on Carpeting FAQs

Thermal tracking stains on carpet in the middle of a room?

Have you ever seen this in carpet in the middle of a room (not near the baseboards). I received a moisture meter to check some ceiling stains to see if they were active or inactive after the former owner replaced the roof. I was using the moisture meter to check the basement- all surfaces.

I found some areas in the basement carpet where the moisture meter was high but dry to the touch. I run a humidifier in that room and it doesn't work very hard to maintain 45-50 rh%

It has a 'line' type stain. A bit darkened (carpet is grey, so this is darkish grey), but not like the other areas where there is actual infiltration soiling (I have seen it is one room near the baseboards but is completely dry). My home is old, so of course it has air leaks.

The former owners had a couch over this area, so I thought it was due to that. Adjacent staining is yellow coloring and also shows moisture in the meter. So moisture and a line/ghosting in carpet. The carpet is gross anyway, so I thought about peeling it back to see if there is a crack in the slab (60+ yr old house).

A contractor friend, without seeing it, said it was radon gas escaping. That seemed like a stretch, since Radon is colorless. I think though, perhaps he meant, air is feeding through the crack and depositing soil on the carpet.

If I do find a crack- should is seal it with concrete/caulk and re-carpet and be vigilant about dehumidification? (Oct 7, 2014) Brennan said:

Reply:

Brennan

Radon gas does not leave black stains in buildings. That contractor friend is simply wrong.

But indeed radon gas moves upwards through points of air leakage in a building, so that might be behind his comment.

We see air bypass leak stains on carpets where there is air movement such as around floor HVAC registers or at a leaky wall-floor juncture. So that's at the edges not in the center of carpeting (unless there's an unusual air bypass leak in the center of the floor).

A couple of points to consider:

Most moisture meters, if we exclude thermal imaging, rely on measuring differences in electrical resistance to detect moisture.

See MOISTURE METER STUDY 

And thermal imaging itself relies on temperature differences. (For example a wet area or an area of air leakage will show up as cooler.)

See and THERMAL IMAGING, THERMOGRAPHY

But other contaminants or materials can also decrease resistance in an area of building material.

So not every reading variation is necessarily truly detecting moisture. Some attention, particularly looking for possible moisture sources, are key.

Both pin type moisture meters (Delmhorst for example) and electronic moisture meters (such as some Tramex meters) can be fooled by metal nearby: pipes, foil faced insulation, wiring.

Second: no moisture meter, nor thermal imaging device, can detect old leaks that have since dried, even though the leak might have initiated a building problem with rot, insect damage, or mold contamination.

This is why we argue that reliance on meters and imaging alone for water or mold detection are unreliable. But the instruments are indeed useful, in thoghtful hands. And neat too.

See THERMAL IMAGING, THERMOGRAPHY

and be sure to review the carpet stain causes

at CARPET STAIN DIAGNOSIS 

Brennan said: Salt from pet urine can also draw moisture from the air

Thanks for your comment. One thought (using my science background) was that the moisture meter gives a high reading on what looks like an old dog urine stain (former owner had dog).

I had the thought that these left over salts and ions from the urine might act as a weak conductor and activate the moisture meter.

On the internet, it seems that carpet companies use moisture meters to find hidden pet stains, because the salt from the urine can draw moisture from the air (or even just the natural evaporation of the concrete slab).

So, thanks for your help. I tend to over-think things. I agree, it is a neat tool.

(mod) said:

Interesting Brennan, and thoughtful. I agree with the salts / ions theory for both of the reasons you offer.

It's not over-thinking. The more we understand the better we can find and fix or prevent aggravations. Thanks.